Gamma-stable high pressure stopcock

ABSTRACT

A medical stopcock is provided that is constructed and arranged to withstand high pressures and gamma irradiation. The stopcock generally includes a housing and a valve member. The valve member is trapped within the housing so that, when subjected to relatively high pressures, the valve member is unlikely to become separated from the housing. A handle member is attached to the valve member and allows the valve member to be rotated from open to closed positions. In some preferred embodiments, the handle member locks the valve member within the housing, when attached. All of the components are constructed of gamma-stable materials so that the stopcock may be sterilized, in its package, using gamma irradiation.

BACKGROUND OF THE INVENTION

The device of the present invention pertains to a stopcock capable ofwithstanding gamma radiation. The stopcock is constructed and arrangedfor high pressure applications.

Gamma radiation is a form of energy capable of deep penetration. Gammairradiation is the use of gamma radiation to sterilize medical devices.Gamma radiation kills microorganisms throughout a product and itspackaging with very little heating. As a sterilant, gamma radiation isthorough; no area of the product, its components, or packaging is leftwith uncertain sterility after treatment. Furthermore, gamma irradiationleaves no residue.

Traditional sterilization techniques include batch sterilization usingethylene oxide (EtO). EtO sterilization leaves a residue and requires anaeration period prior to shipment. The packaging must be gas permeableto allow the EtO to completely evaporate prior to use. Gas permeablepackaging, however, increases the possibility of contamination overtime. Thus, a relatively early expiration date is assigned to thesterilized device. Gamma radiation, on the other hand, penetratesthrough the packaging and, again, leaves no residue.

Commercially-available stopcocks, however, are constructed of materialsthat are not dimensionally stable when exposed to gamma radiation.Gamma-stable materials are more expensive and more rigid than the softermaterials used to form the valve members of the commercially-availablestopcocks. FIG. 1 shows a cross-sectional view of a typical,commercially-available stopcock 1. The stopcock 1 includes a valvemember 3 inserted into a housing 5. The valve member 3 may be hollow, asshown, or solid and includes a port 7 that can be aligned with passage 9of the housing 5.

The two-piece construction of the stopcock 1 relies on an interferencefit between the valve member 3 and the housing 5. In other words, thevalve member 3 is slightly larger than the interior of the housing 5.When the valve member 3 is inserted into the housing 5, it compressesand forms a fluid-tight fit. Thus, the valve member 3 must beconstructed of a softer plastic than that of the housing 5. Typicalmaterials used to make these valve members 3 include acetal andacrylonitrile butadiene-styrene (ABS).

Unfortunately, these soft materials used to make the valve members 3cannot withstand gamma irradiation. When exposed, the valve members 3change dimension and render the stopcock unusable. Thus, a lesseffective, more expensive, form of sterilization must be used.

Another disadvantage of these stopcocks 1 pertains to the design of thesnap fit between the soft valve member 3 and the housing 5. As seen inFIG. 1, the snap fit arrangement is achieved by providing an angledflange 11 at the lower end of the valve member 3 that is configured tomate with a corresponding inwardly-projecting flange 13 that is integralwith the housing 5. To allow assembly and a fluid tight fit, the flanges11 and 13 have to be relatively small so that the flange 11 on the valvemember 3 may deform and reform as it passes over the other flange 13during assembly. The size relationship between the two flanges 11 and 13limits the use of these stopcocks 1 for high pressure applications. Whensubjected to high pressures, there is a tendency for the valve members 3to be ejected from the housing 5.

A further disadvantage of these stopcocks 1 is that they requireexcessive turning force to open and close the valves. Because thefluid-tight integrity depends on the friction fit between valve member 3and the housing 5, and thus the valve member 3 is slightly larger thanthe housing 5, it is difficult to turn the valve member 3 within thehousing 5. Users complain that two hands are necessary to operate thestopcocks 1 without causing the tubing attached to the stopcocks frombecoming twisted or dislodged. Further, the relatively small size of thestopcocks 1 make it difficult to grasp the housing 5, to turn the valvemember 3, without having fingers interfere with the handle of the valvemember 3. This problem is especially prevalent when turning the valvemembers 3 of high pressure stopcocks while wearing wet rubber gloves.

Additionally, materials like acetal and ABS are opaque, which is yetanother disadvantage. For purposes of blood and bubble detection, it ispreferable to use a fluid network comprised entirely of clearcomponents.

There is thus a need for a stopcock that can withstand gammairradiation.

There is a further need for a stopcock that is constructed and arrangedto withstand high pressures.

There is also a need for a stopcock that can be opened and closed withrelative ease.

There is an additional need for a stopcock that is constructed entirelyof clear materials.

BRIEF SUMMARY OF THE INVENTION

The present invention pertains to a stopcock made entirely of materialscapable of withstanding sterilization using gamma irradiation. A methodof making a stopcock is disclosed that allows a stopcock housing to beformed around the outside of a valve member, thereby providing animproved fit between the valve member and the housing.

The internal valve member is constructed of a rigid material, such aspolyetheretherketone (PEEK), capable of withstanding gamma rays withoutexperiencing a change in dimension. The external housing is alsoconstructed of such a material, usually polycarbonate. The housingincludes a cylindrical interior cavity with an inner diameterapproximately equal to the outer diameter of the valve member. The valvemember has a stop, preferably a flange, extending radially from one endto prevent the valve member from passing completely through the housing.The valve member is secured at the other end by attaching a handlemember thereto. The attachment is made with an adhesive, snap fit,friction fit, weld (e.g. ultrasonic), pin connection, or the like.

PEEK is just an example of many materials acceptable for use in makingthe stopcock of the present invention. Other example materials includepolyesters, glycol modified polyethylene terepthalate (PETG),polycarbonate, polycarbonate alloys, polysulfone, polyurethane,polyetherketoneketone (PEKK), polyetherimide, thermosets, polyamides,polyaryletherketone (PAEK), and flouroplastics other thanpolytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP).Examples of acceptable thermosets include polyimides, polyurethanes, andpolyesters.

The handle member, valve member and housing all may be made of the samematerial. However, using materials having slightly different meltingpoints for the housing and the valve member provides an advantageousmanufacturing option. If the housing is made of a material with aslightly lower melting point than that of the valve member, the housingmay be formed by over molding the valve member. This ensures that theinterior cavity of the housing exactly matches the size of the valvemember. The difference in melting temperature prevents the housingmaterial from fusing with the valve member.

Alternatively, the process of over-molding may use materials that arenot considered gamma-stable as a way of ensuring a close fit between theouter housing and the inner valve member. If the inner valve member andthe outer housing are made of materials that react differently whenexposed to gamma radiation, the outer housing may be made to shrinkaround the inner valve member during gamma irradiation. This concept notonly creates a water-tight fit between the housing and the valve member,it permits the use of less expensive, non-gamma-stable materials.

Additionally, considering the high cost of gamma-stable materials, itmay be desired to provide a non-gamma-stable handle, attachable to agamma-stable valve member. Doing so would not only provide a costbenefit, especially in the case of large stopcocks, it would also allowdesign flexibility. For example, it may be desired to provide a varietyof handle members having different colors. The colors could then beselected to identify the type of fluid travelling through the stopcock.The valve member may also be designed without a handle, for use with anautomatic device constructed and arranged to operate the stopcock.

Further, to provide turning ease, a grip is preferably incorporated intothe stopcock housing which can be used to hold the housing while turningthe valve member, thereby giving the physician greater turning leverage.The grip may be an axial extension of the housing or may extend radiallyin a direction where interference with ports is not created.

One aspect of the present invention provides a stopcock having a valvemember that is attachable to, or integral with, handle members on eitherside of the stopcock.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a prior art stopcock;

FIG. 2 is a perspective view of a preferred embodiment of the stopcockof the present invention with the handle member separated from the valvemember and the housing partially cut away;

FIG. 2A is a perspective sectional view of an alternative embodiment ofa stopcock of the present invention with the handle member separatedfrom the valve member;

FIG. 3 is a perspective view of a stopcock housing of the presentinvention;

FIG. 4 is a perspective view of a valve member of the present invention;

FIG. 5 is a cutaway elevation of another preferred embodiment of thestopcock of the present invention;

FIG. 6 is a partial perspective view of an embodiment of the second endof the housing of the present invention;

FIG. 7 is a cutaway elevation of yet another preferred embodiment of thestopcock of the present invention;

FIG. 8 is a perspective view of a preferred embodiment of a stopcock ofthe present invention, and;

FIG. 9 is a perspective view of another preferred embodiment of astopcock of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 2, there is shown a stopcock 10 of the presentinvention. The stopcock 10 generally comprises a housing 12, a valvemember 14, and a handle member 16. The housing 12, the valve member 14and the handle member 16 are all preferably made of materials thatremain dimensionally stable when exposed to gamma radiation.

The housing 12 is best shown in FIG. 3 and includes at least one inletport 18 and at least one outlet port 20. Both ports 18 and 20 lead intoan interior cavity 22 sized to receive the valve member 14. Notably, thehousing 12 is open at a first end 24 and a second end 26, defining thelimits of the interior cavity 22. The importance of these open ends 24and 26 is discussed below.

FIG. 4 shows a valve member 14. The valve member 14 generally comprisesa cylinder sized to be rotatably contained within the interior cavity22. The valve member 14 includes a first end 28 and a second end 30 thatcorrespond to the first and second ends 24 and 26 of the housing 12 whenassembled. The second end 30 of the valve member 14 includes a stop 32preferably in the form of a flange. The stop 32 is sized to interferewith the opening at the second end 26 of the housing 12. The stop 32thus prevents the valve member 14 from being removed from the housing 12through the first end 24 of the housing 12. The valve member 14 furtherincludes a passage 34 that is alignable with the ports 18 and 20 of thehousing 12 when it is desired to establish fluid communication betweenthe ports 18 and 20. Additionally, at the first end 28 of the valvemember 14, there is an attachment area 36, usable to attach the valvemember 14 to the handle member 16.

The handle member 16 is shown in FIG. 2 and includes an attachment area38 that is configured to mate with the attachment area 36 of the valvemember 14. The attachment areas 36 and 38 are shown in FIGS. 2 and 4 asbeing square female and male couplings, respectively. One skilled in theart will understand that many configurations would perform the desiredfunction of attaching the handle member 16 to the valve member 14. Themale and female coupling arrangement shown in the Figures serves toprovide adequate surface area for the application of adhesive, ifdesired, and also provides sufficient structural interaction between thevalve member 14 and the handle member 16 to allow the handle member 16to be used to twist the valve member 14. The handle member 16 furtherincludes a contact surface 40. When the handle member 16 is attached tothe valve member 14, the contact surface 40 acts against the first end24 of the housing 12. The contact surface 40 and the stop 32 togetherprevent the valve member 14 from moving axially, relative to the housing12. Thus the valve member 14 is axially locked within the housing 12,yet still allowed to rotate.

FIG. 2A shows an alternative preferred configuration for attaching thehandle member 16 to the valve member 14. Handle member 16 includes aslot 17 configured to mate with a valve member extension 19. Preferablythe valve member extension 19 forms a snap lock fit with the slot 17.When the handle member 16 is snapped onto the valve member 14, theunderside of the handle member 16 forms the contact surface 40, whichacts against the first end 24 of the housing 12 to prevent the valvemember 14 from becoming disengaged from the housing 12.

The materials used to make the housing 12, the valve member 14, and thehandle member 16, are preferably clear and gamma-stable, and thus allowthe entire valve to be assembled and packaged prior to sterilizationusing gamma irradiation. Depending on the manufacturing method chosen tomake the valve 10, discussed below, the materials used in the housing12, the valve member 14, and the handle member 16 may be the same ordifferent. For example, to reduce costs, the handle member may be madeout of less expensive, non-gamma-stable materials. Acetal and ABSprovide two examples of acceptable materials.

Gamma-stable materials, acceptable for use in making the valve 10 of thepresent invention include PEEK, polyesters, PETG, polycarbonate,polycarbonate alloys, polysulfone, polyurethane, PEKK, polyetherimide,thermosets, polyamides, PAEK, and flouroplastics other than PTFE andFEP. Examples of acceptable thermosets include polyimides,polyurethanes, and polyesters. These materials are provided by way ofexample and are not intended to represent an exclusive list ofacceptable materials. Any gamma-stable material exhibiting sufficientstructural integrity is acceptable.

Once materials are selected and used to form the housing 12, valvemember 14 and handle member 16, the valve 10 is assembled by introducingthe first end 28 of the valve member 14 into the second end 26 of thehousing 12. The valve member 14 slides into the interior cavity 22 ofthe housing 12 until the stop 32 abuts against the second end 26 of thehousing 12. Next the handle member 16 is attached to the valve member 14by aligning the respective attachment areas 36 and 38 with each other,and securing them together using a gamma-stable adhesive, ultrasonicweld, mechanical connection, or the like.

Various embodiments of the present invention provide a stopcock 10whereby the handle member 16 and the valve member 14 are integral. Onesuch embodiment is shown in FIG. 5. The valve member 14 defines a hole42 at its second end 30 through which a pin 44 is placed after the valvemember 14 is inserted into the housing 12. A stop (not shown) may beprovided to act against the first end 24 of the housing 12, such as stop40 shown in FIG. 2. Alternatively, as shown in FIG. 5, the valve member14 and the interior cavity 22 are slightly conical, obviating the needfor a stop 40, and better ensuring a seal is formed between the valvemember 14 and the housing 12. The hole 42 is placed to create a slightdownward force on the valve member 14 when the pin 44 is in place.

FIG. 6 shows an embodiment of a housing 12 that is shaped to increasethe downward force on the valve member 14. The second end 26 of thehousing 12 is shaped to form a recessed area 46 that provides adequateclearance to place the pin 44 through the hole 42 in the valve member14, when the hole 42 is aligned with the recessed area 46.

Adjacent to the recessed area 46 is an angled ramp surface 48. Once thepin 44 is in place, the valve member 14 is rotated so that the pin 44meets with increasing resistance by the ramp surface 48, as the valvemember 14 is pulled deeper into the interior cavity 22. If the valvemember 14 and interior cavity 22 are conical, this ramp effect creates agreater seal between the side wall of the valve member 14 and the innerside wall of the housing 12 defining the interior cavity 22. If acylindrical valve member 14 and interior cavity 22 are used, along witha stop 40 such as that shown in FIG. 2, the ramp effect creates atighter seal between the stop 40 and the first end 24 of the housing 12.

At the end of the angled ramp surface 48 is a catch 50. Once the valvemember 14 is rotated sufficiently, the pin 44 will overcome the ramp 48and snap behind the catch 50. The catch 50 prevents counter rotation ofthe valve member 14 to the extent that the pin 44 reenters the recessedarea 46 and becomes dislodged. The catch 50 thus defines a rotationallimit on the valve member 14.

Adjacent the catch 50 is an operating surface 52. This surface 52 isrelatively parallel to the plane the pin 44 defines as the valve member14 is rotated. Preferably, the operating surface 52 also includes levelportions 53 and tightening portions 55. The level portions 53 arepositioned to provide a minimal amount of downward force on the pin 44so the valve member 14 may be rotated with ease. The tightening portions55 are positioned to correspond with alignment positions between thevalve member passage 34 and the housing ports 18 and 20. Thus, when thevalve member 14 is in alignment with the ports of the housing 12, thevalve member 14 is pulled into tight contact with the interior walls ofthe housing 12, thereby creating a fluid-tight seal acceptable for highpressure operation. A notch 57 may be included to provide a tactilefeedback to the operator as to when the valve member 14 is in alignmentwith the housing ports 18 and 20. The angular operating range of thevalve member 14 is defined at one extreme by the catch 50, as discussedabove, and is defined at an opposite extreme by a rotational stop 54.The rotational stop 54 prevents the pin 44 from rotating to the pointwhere it enters the recessed area 46 on the opposite side of the housing12, designed to accommodate the other end of the pin 44.

One manufacturing method of the present invention allows the use of avalve member 14, which is integral with a handle member 12, and does notrequire the use of a pin 44. FIG. 7 shows an embodiment of stopcock 10whereby the valve member 14 and the interior cavity 22 of the housing 12are curved such that the first end 24 and the second end 26 of thehousing 12 are narrower than the other parts of the housing 12. Thus,the valve member 14 is locked inside the housing 12.

To manufacture the stopcock 10 of FIG. 7, the valve member 14 is moldedof a first gamma-stable material. A rod (not shown) is then placedthrough the passage 34 to keep the passage 34 open during the remainderof the manufacturing process and to form the inlet port 18 and outletport 20 of the housing 12. The housing 12 is then cast around the valvemember 14 and rod using a second gamma-stable material that has a lowermelting temperature than that of the first gamma-stable material. Usingmaterials with different melting points and different moldingtemperatures ensures that the valve member 14 won't melt and adhere tothe housing 12. A light agent, such as a lubricant, may be applied tothe valve member 14 to further prevent the housing 12 from adheringthereto. For example, PEEK may be used as a first material to make thevalve body 14. Polycarbonate could then be used as the second materialto mold the housing 12. Polycarbonate has a melting temperature of about540-575° F. but a relatively low molding temperature of about 150-220°F.

Once the housing 12 has solidified, the rod is removed and the valvemember 14 may be rotated within the housing 12. An alternative tocasting the housing 12 around the valve member 14 is a dip coatingprocess whereby the valve member 14 and rod are repeatedly dipped into aliquid volume of the second material to form the housing 12.

FIG. 8 is a preferred embodiment of the stopcock 10 of the presentinvention. The stopcock 10 is shown as a three-way stopcock with oneinlet port 18 and two outlet ports 20. A flange 60 is integral with theports 18 and 20 and extends therefrom. The flange 60 may be a differentmaterial than the rest of the housing 12 but is preferably the samematerial. The flange 60 adds rigidity to the housing 12 for highpressure operations and also provides an area 62 to grip the valve 10while turning the handle member 16. Gripping the flange 60 providesincreasing turning power and prevents fingers from interfering with themovement of the handle member 16.

FIG. 9 is another preferred embodiment of the stopcock 10 of the presentinvention. The stopcock 10 is shown as a three-way stopcock with oneinlet port 18 and two outlet ports 20. A grip 64 extends from thehousing 12 at an angle that does not interfere with the range of motionof the handle member 16, the various positions of which are shown inphantom lines. Like the flange 60 shown in FIG. 8, using the grip 64increases turning power and prevents fingers from interfering with themovement of the handle member 16.

The foregoing description addresses embodiments encompassing theprinciples of the present invention. The embodiments may be changed,modified and/or implemented using various types of arrangements. Forexample, the stopcock of the present invention has been herein describedas pertaining to medical applications. However, it is envisioned, andwould be clear to one skilled in the art, that the teachings of thepresent invention could be applied to applications in fields such aselectronics, microbiology, or others requiring sterility. Thus, thoseskilled in the art will readily recognize various modifications andchanges that may be made to the invention without strictly following theexemplary embodiments and applications illustrated and described herein,and without departing from the scope of the invention, which is setforth in the following claims.

1-39. (canceled)
 40. A stopcock, comprising: a housing constructed fromgamma-susceptible material defining an inlet port, at least one outletport, and an interior cavity having an inner diameter and open at twoopposing ends; a valve member constructed from gamma-stable materialrotatably contained within said interior cavity, defining a passagealignable with said ports, and having: an outer diameter less than saidinner diameter; and a handle member, attached to an opposite end of saidvalve member, constructed and arranged to allow rotation of said valvemember and to prevent said valve member from becoming separated fromsaid housing; wherein said housing forms a seal with said valve memberand said valve member is retained within said housing after exposure ofsaid housing to gamma radiation.
 41. The stopcock of claim 40 furthercomprising a weld connecting said handle member to said valve member.42. The stopcock of claim 40 further comprising a pin connecting saidhandle member to said valve member.
 43. The stopcock of claim 41 whereinsaid weld comprises an ultrasonic weld.
 44. The stopcock of claim 40further comprising an adhesive connecting said handle member to saidvalve member.
 45. The stopcock of claim 40 wherein said housingcomprises a material selected from the group: acetal and ABS.
 46. Thestopcock of claim 40 wherein said handle member comprises a materialselected from the group: acetal and ABS.
 47. The stopcock of claim 40,further comprising a stop at an end of said valve member extendingradially therefrom; wherein said stop is rendered unable to pass throughsaid interior cavity after exposure of said housing to gamma radiation.48. The stopcock of claim 40 wherein said valve member comprises amaterial selected from the group: polyesters, PETG, polycarbonate,polycarbonate alloys, polysulfone, polyurethane, PEKK, PEEK, PAEK,polyetherimide, thermosets, polyamides, and flouroplastics other thanPTFE and FEP.
 49. The stopcock of claim 48 wherein said thermosetscomprise the group: polyimides, polyurethanes, and polyesters.
 50. Thestopcock of claim 40 wherein said handle member and said valve memberare made of the same material.
 51. The stopcock of claim 47 wherein saidhandle member and said valve member are made of the same material. 52.The stopcock of claim 40 further comprising a flange, extending from thehousing, providing a gripping area.
 53. The stopcock of claim 47 furthercomprising a flange, extending from the housing, providing a grippingarea.
 54. The stopcock of claim 52 wherein said flange is integral withthe housing.
 55. The stopcock of claim 53 wherein said flange isintegral with the housing.
 56. The stopcock of claim 40 wherein saidseal is formed by shrinkage of said housing member.
 57. The stopcock ofclaim 47 wherein said valve member is rendered unable to pass due toshrinkage of said housing after exposure of said housing to gammaradiation.
 58. The stopcock of claim 40 wherein said seal is formed whensaid inner diameter is substantially equal to said outer diameter. 59.The stopcock of claim 47 wherein said valve member is rendered unable topass when said stop extends beyond the dimension of said inner diameter.60. A stopcock comprising: a housing constructed from gamma-susceptiblematerial and defining an inlet port, at least one outlet port, and aninterior cavity having an inner diameter and open at two opposing ends;and a valve member constructed from gamma-stable material, said valvemember rotatably contained within said cavity and defining a passagealignable with said ports; wherein said housing assumes at least onedesired final dimension after exposure to gamma radiation.
 61. Thestopcock of claim 60, further comprising a stop operably attached to anend of said valve member, constructed and arranged to prevent said valvemember from passing completely through the said cavity of said housing.62. The stopcock of claim 60, further comprising a handle member,operably attached to an end of said valve member, constructed andarranged to allow rotation of said valve member and to prevent saidvalve member from becoming separated from said housing.
 63. The stopcockof claim 60 wherein the at least one outlet port comprises one outletport.
 64. The stopcock of claim 60 wherein the at least one outlet portcomprises two outlet ports.
 65. The stopcock of claim 61 wherein saidstop extends radially from the valve member.
 66. The stopcock of claim60 wherein said desired final dimension of said housing is the diameterof said cavity.
 67. The stopcock of claim 62, wherein said desired finaldimension of said housing is the diameter of said cavity, and whereinsaid diameter is smaller than the corresponding dimension of said stop.68. The stopcock of claim 60 wherein the interior cavity of said housingdimension is substantially equal to the outer dimension of said valvemember.
 69. The stopcock of claim 61 wherein the interior cavity of saidhousing dimension is substantially equal to the outer dimension of saidvalve member.
 70. The stopcock of claim 62 wherein the interior cavityof said housing dimension is substantially equal to the outer dimensionof said valve member.
 71. The stopcock of claim 60 wherein said finaldimension of said housing forms a seal with said valve member.
 72. Thestopcock of claim 61 wherein said housing having said final dimensionhousing forms a seal with said valve member.
 73. The stopcock of claim62 wherein said final dimension of said housing forms a seal with saidvalve member.
 74. The stopcock of claim 60 wherein said valve membercomprises a material selected from the group: polyesters, PETG,polycarbonate, polycarbonate alloys, polysulfone, polyurethane, PEKK,PEEK, PAEK, polyetherimide, thermosets, polyamides, and flouroplasticsother than PTFE and FEP.
 75. The stopcock of claim 61 wherein said valvemember comprises a material selected from the group: polyesters, PETG,polycarbonate, polycarbonate alloys, polysulfone, polyurethane, PEKK,PEEK, PAEK, polyetherimide, thermosets, polyamides, and flouroplasticsother than PTFE and FEP.
 76. The stopcock of claim 62 wherein said valvemember comprises a material selected from the group: polyesters, PETG,polycarbonate, polycarbonate alloys, polysulfone, polyurethane, PEKK,PEEK, PAEK, polyetherimide, thermosets, polyamides, and flouroplasticsother than PTFE and FEP.
 77. A stopcock comprising: a valve member of afirst gamma-stable material having a longitudinal axis and a passagetherethrough transverse to said longitudinal axis; a housing of agamma-susceptible material defining an inner cavity for the valvemember, the housing having at least one open end and defining at leastone inlet port and at least one outlet port, the ports alignable withsaid passage; wherein the valve member has varying circularcross-sectional areas measured in planes perpendicular to thelongitudinal axis, cross-sectional areas toward a middle of the valvemember being greater than the cross-sectional areas toward ends of thevalve member, and said inner cavity is sized to accept passage of thevalve member during assembly; and wherein the inner cavity assumes ashape that conforms to the valve member through exposure to gammaradiation such that the housing and the valve member are shaped to allowrotation of the valve member around the longitudinal axis, relative tothe housing, and to prevent movement in either direction along thelongitudinal axis, relative to the housing.
 78. The stopcock of claim 77wherein said housing further comprises a closed end, wherein the openend defines an opening having a cross-sectional area substantially equalto the cross-sectional areas toward the middle of the valve memberbefore gamma irradiation and a cross-sectional area smaller than thecross-sectional areas toward the middle of the valve member after gammairradiation.
 79. A stopcock, comprising: a valve housing; and a valvemember placed inside the valve housing, such that when the stopcock isexposed to gamma irradiation, the valve housing assumes a finaldimension relative to the valve member.
 80. The stopcock of claim 79,wherein the valve housing is constructed from gamma-susceptiblematerial.
 81. The stopcock of claim 79, wherein the valve member isconstructed from gamma-stable material.
 82. The stopcock of claim 79,wherein the valve housing shrinks to form a seal with the valve memberupon exposure of the stopcock to gamma irradiation.
 83. The stopcock ofclaim 79, wherein the valve housing defines an inlet port, at least oneoutlet port, and an interior cavity.